Foa is an island in Tonga. It is located within the Haʻapai group in the centre of the country, to northeast of the national capital of Nukuʻalofa.
Foa is linked to adjacent Lifuka Island by a causeway, and is located 640 meters northeast of Lifuka.
The island has an area of 13.39 km². In 1996, the population numbered 1,434. It rose to 1,485 in 2006.